Guess i fixed it, i think i forgot to edit the default communication port during migration, standard is 8014. My iis Symantec Webserver is configured on port 80, during migration the altered settings in the past are not changed but left on port 80.
I changed the communication port in SEPM to 80, clients tryed to communicate on port 80, SEPM was 8014 default.

It seems i fixed it "again"..? maybe it was a different issue then yesterday i dont know about that.

I followed this document: http://www.symantec.com/business/support/index?page=content&id=TECH161964
How to bypass the IIS Proxy to apache webserver, it seems like this was giving me issueswith disconnecting clients.

I migrated my old SEPM 11.0.7 with the following configuration:
1 site, in this site 2 SEPM servers configured as fail-over.
I noticed on my main SEPM server the iis bypass to apache, this i changed like described in the document: http://www.symantec.com/business/support/index?page=content&id=TECH161964

I noticed on my fail-over SEPM server the migration just deleted my IIS symantec webserver, only running on apache i guess.

Well i hope the changes in the SEPM communication ports and the changes in IIS bypass to apache solved my issue and keeps it solved :)